COLUMNARIADyE. • 191 



having come under my observation. The size of ordinary 

 specimens varies from an inch or less in height and breadth up 

 to half a foot or more. 



Formation and Locality, — Abundant in the Lower Silurian 

 Limestone of Craighead, Girvan, Ayrshire. 



Genus Columnaria, Goldfuss, 1826. 



(Petref. Germ., t. i. p. 72.) 



Columnaria (pars), Goldfuss, Petref. Germ., t. i. p. 72, 1826. 

 Favistella} Hall, Pal. N.Y., vol. i. p. 275, 1847. 

 Favistella, Nicholson, Sec. Rep. Pal. Ont., p. 21, 1875. 



Gen. Char. — Corallum composite, massive, composed of poly- 

 gonal, closely-compacted and contiguous corallites, which are 

 united by their walls, but do not possess mural pores. Walls 

 of the corallites not excessively thickened. Septa well devel- 

 oped, typically extending nearly to the centre of the visceral 

 chamber, and alternately large and small. Tabulae extremely 

 well developed, complete, and horizontal. No columella or 

 coenenchyma. 



Obs. — This genus was founded by Goldfuss to include certain 

 massive aggregate corals, which closely resemble Favosites in 

 general appearance, but differ in having lamellar septa and im- 

 perforate walls. Of the three forms included by Goldfuss under 

 this name, two appear to be compound Rugose corals, as shown 

 by Milne-Edwards and Haime (Pol. Foss. des Terr. Pal, p. 

 308, 1 851); and the title Columnaria can therefore only be 

 retained for the third of these — viz., C. alveolata, which occupies 

 the first place in the original description, and must therefore 

 be strictly regarded as the type-species. Nor can any doubt be 



^ The name of Favistella was proposed in 1846 (U.S. Expl. Exped. Zooph., p. 

 538) by Dana for "a part of the true Favosites, in which the cells are stellate with 

 twelve distinct rays." There is, however, no sufficient evidence that Dana had in 

 view the true Columnarice, rather than the similar-looking forms of Favosites with 

 well-developed septa ; and it is quite clear that Hall introduced the name Favistella 

 quite independently. 



